Crime Scene 101: Locating and Documenting Evidence

At the heart of every crime scene are two basic questions for the Crime Scene Officer: how do you find the evidence and how do you properly document it once you find it? Finding the evidence is essential to building a solid case; in fact, if you don’t collect all of the evidence at the scene, you could jeopardize the outcome of a court case. Equally important is documenting it properly. If you locate every piece of evidence but fail to document each item carefully, the evidence may end up being worthless in court.

One of the keys to locating evidence at a crime scene is proper lighting. While lighting is especially important at night, you may also need additional lighting during the day. You still need a flashlight, but just using a flashlight isn’t enough—you’ll miss things that way. And when you’re indoors, don’t be afraid to turn on all the lights—it isn’t like T.V. where they do everything in dim light for effect. But sometimes, even your flashlight and every light in the building isn’t enough. Imagine, for example, that you’re working a homicide that occurred in a bedroom. You may be there during the day, but it may be raining or the bedroom lights may not throw much light.When you’re searching for evidence, you need to look under the beds, behind the dresser, in the closets, etc. You can’t conduct this kind of search without enough light.

CSOs have many options for lighting. Most important, you want the scene as bright as day. If you have an outdoor scene at night, you’ll need large lights. Even if the scene is primarily inside a residence or other building, you still need lights to illuminate the exterior. You have a wide choice of lights—basic lights that plug into an outlet and are available at hardware stores; larger lights that require generators; and newer versions that use LEDs. Prices range from $30 to several thousand dollars. Depending on your department’s budget and your needs, you could equip each CSO’s vehicle with standard lights that are 110 volts and about 10-12 inches across. These lights provide enough detail to find evidence, and they are also easy to transport and relatively inexpensive. Again, depending on your department’s budget you may also want to invest in one or two really powerful lights for the times when you’re processing outdoor scenes at night. If nothing else, do what I’ve done when I had no other options—bring in a fire truck and use their lights.

Now, you may be thinking that it would be easier to wait until daytime to process an outdoor scene. If you do that, you may end up ruining your case. Waiting until daytime may compromise your evidence. If the weather changes, for example, you could lose evidence or have trouble finding it. In addition, if you wait to process the scene, an officer has to stay at the scene to secure it. What happens if that officer leaves? I once had a case where we began working in daylight and then left 14 hours later, at 2 a.m., to get a couple of hours of rest. Although we left two officers at the scene, when we came back, they were gone because the night commander pulled them off. We then had to get another search warrant. Such situations can create questions about chain of custody. Thank goodness we took the collected evidence with us, so it was not compromised.

While finding evidence is important, documenting it is also essential. In order to do it right, you need to photograph the scene, use scales or other markers with the photographs, collect the evidence, and then record the information about the evidence on the Evidence Custody Sheet.

When you photograph the scene, first, take enough photographs. It’s not unusual to take 200-400 photos of a major crime scene, and with digital cameras there’s no reason not to take as many photos as you need. On the other hand, don’t take pictures just to take pictures— make sure you’re taking photos of things that are relevant to the case. Remember that everything you photograph goes to the defense, so don’t photograph (or videograph) anything inappropriate. Finally, take photos that capture all perspectives of the scene; in other words, take photos that show an overall view, a medium view, and close-ups. Close-up photos should include a scale and a frame marker, which will correspond with the item number used on the Evidence Custody Sheet. Some CSOs make the mistake of photographing evidence in isolation. For example, someone might shoot a close-up of blood spatter on a wall without any scales or frame markers, or any other photos of the rest of the room for reference. Such a photo is not useful in court. Instead, begin by photographing the entire room. Then focus on the part of the room where the evidence is. Finally, shoot individual close-ups of each piece of evidence with a scale inserted.

Once you’ve photographed the evidence, collect the evidence and prepare the Evidence Custody Sheet, a report which documents all of your evidence. Here you record each piece of evidence along with its item number, what was done with it, where it was found, etc. The item number for each piece of evidence must correspond with the number found on the photograph of the item and the number entered on any evidence collection bags, etc.

As CSOs, we should assume that every crime scene will lead to a jury trial, and our job is to collect evidence and document it so that prosecutors can get convictions. After all, the prosecutors aren’t on the scene; they’re relying on us to make their case. If we do our jobs in a careful, systematic way, we’ll do a good job; if we do our jobs in a haphazard manner, we won’t have much to give the prosecutors. Working a crime scene is like working a puzzle. You build from the outside and work your way in until you solve the case—but if you aren’t careful, if you miss evidence, you’ll be left with just the perimeter of the puzzle instead of the solution.

Dick Warrington is in research and development and a crime scene consultant and training instructor for the Lynn Peavey Company. Dick can be reached at dwarrington@peaveycorp.com.